1. Technical Field
The subject invention relates to apparatus and method of testing insulating arm sleeves such as those used in combination with insulating gloves in the electrical power industry for maintenance of live power lines. More particularly, the invention relates to electrical insulating arm sleeves in which the complete arm sleeves are tested for electrical defects in an efficient and safe manner for use and protection when handling live power lines.
2. Background Information
Electrical testing of insulating arm sleeves used by electricians and electrical utility linemen for performing live line maintenance work has been conducted heretofore to detect defects or flaws in such sleeves to ensure their safe use to prevent electrical shock injury to such workers. Previously, the smaller end of such frusto-conical shaped arm sleeves has been retained within a bath of Freon liquid while the sleeves are partially immersed in a tank of different conductive liquid. An electrode is introduced into the sleeve which is filled with a conductive liquid to essentially the same level as in the tank. An electrical potential is established between the conductive liquids in the sleeve and the immersion tank, the electrical potential difference between the liquids causing a breakdown in the sleeve at damaged or defective areas. Normally, such breakdown actuates a visible signal or an audible alarm during the performance of the sleeve testing procedure.
In related test procedures which are made on many types of insulating gloves, disadvantages have been found in placing electrical stresses at the junction of the water surface and cuff of the glove. Such stresses which occur at the water surface attain such level whereby the surrounding air is ionized resulting in the production of ozone and corona effects. Most insulating gloves being comprised of natural or synthetic rubber are adversely affected by the occurrence of ozone which is destructive of such materials. The high electrical stress which occurs at the top area frequently results in excessive glove failure during tests. Such gloves have also required that they have relatively long cuff areas to enable the gloves to be adequately tested. Such increased cuff lengths on the glove make the gloves more cumbersome for wear during their use as well as adding to their cost of manufacture.
The aforesaid testing of gloves is relatively easy to perform where the gloves have only one cuff opening and are able to contain the conductive liquid with the cuff opening held upright. The arm sleeves being tubular having upper and lower openings cannot be similarly tested unless the lower opening is sealed to contain the liquid during testing.
The testing of insulated arm sleeves utilizing Freon liquid to contain the smaller end of the sleeves is one which must be avoided in view of restricted use of Freon-type materials which are considered to possess toxic properties. The smaller end of the sleeves must be retained in liquid-tight closed relation in order to perform the electrical testing by means of the two electrically-isolated conductive liquids on both sides of the sleeves. The smaller ends must be restrained in pressure tight relation by non-metallic elements which facilitate establishing the electrical potential difference between opposite sides of the sleeve to detect manufacturing flaws or damaged areas incurred during previous use. Such repeated testing on both new and used arm sleeves is imperative in view of the hazardous conditions encountered by workmen in the electrical power industry who are required to wear such protective safety apparel.